Full stroke compelling mechanism having a pressure responsive valve member within the working chamber



1968 P. J. SPANGLER ETAL 3,4 0,

FULL STROKE COMPELLING MECHANISM HAVING A PRESSURE RESPONSIVE VALVE MEMBER WITHIN THE WORKING CHAMBER Filed Aug. 3, 1966 5 Sheets-Sheet l A v N 0+ i mm fi .9. Oh v mm 8 E 9Q. 2. mm & mm mm H vw om. 8 /7///////// 2 2 v O .V Q 0E mm 2 2 mv mm Q 5 mm M x M. mm c 1 .U m. S 4 i... h Nw NN 3 on $3 vm mm 9 mm r///////// \,v/ /-///%//////////V//////// IJ NV I V N :v S mm 9 mm mm INVENTOR. 2% W? BY v J ATTORNEYS N V- 1968 P. J. SPANGLER ETAL 10,180

FULL STROKE COMPELLING MECHANISM HAVING A PRESSURE RESPONSIVE VALVE MEMBER WITHIN THE WORKING CHAMBER Filed Aug. 5, 1966 3 Sheets-Sheet 2 INVE OR ED W eaFD ER I Tm BY ha Nov. 12, 1968 P. J. SPANGLER ETAL. 3,410,180

FULL STROKE COMPELLING MECHANISM HAVING A PRESSURE RESPONSIVE VALVE MEMBER WITHIN THE WORKING CHAMBER Filed Aug. 3, 1966 3 Sheets-Sheet 3 INVENTOR. m;- aamm 511% I ATTORNEYS United States Patent ABSTRACT OF THE DISCLOSURE A mechanism for insuring the full stroke of a fluidoperated piston within a cylinder. A normally open valve is provided in a wall portion of the cylinder and the valve is closed by the piston only when the piston completes a full stroke. If a *full stroke does not obtain and the valve is not closed, piston return pressure will be exhausted through the open valve. 20

This invention relates to a full stroke compelling mechanism and, more particularly, to full stroke compelling mechanisms for fluid actuated hand tools which may be employed to crimp the ferrule portion of electrical connectors to their conductors.

Fluid actuated compression tools for forging electrical connectors onto conductors and for other similar operations generally comprise a fluid actuated piston and a 0 jaw or pair of jaws mechanically actuated by the piston rod. The actuating connection between the piston rod and the jaw or jaws usually includes a linkage or calm arrangement that displaces the jaw or jaws in response to movement of the piston. The jaws are closed when the piston is driven toward the jaws by the fluid pressure and the jaws are opened by applying fluid pressure to the opposite side of the piston and by simultaneously exhausting the fluid pressure which was employed to drive the piston toward the jaws.

In the use of such a tool for crimping the ferrule portion of electrical connectors, it is highly important that the jaws be closed to a preselected position in order to apply a predetermined crimping force to the ferrule. In some instances, the tool operator may not operate the valve which admits air behind the piston for a sufiicient time to insure a full stroke of the piston. In such a situation, the crimping jaws will not be closed to their preselected position.

It is an object of the present invention to provide a device for insuring the full stroke of a piston in a cylinder.

It is a more particular object of the present invention to provide a device which will insure the full stroke of a piston within the cylinder of a hand crimping tool by preventing retraction of the piston unless the full stroke has been accomplished.

It is a further object of this invention to provide a device which will insure the full stroke of a piston within a cylinder and which will prevent operation of the piston if the fluid pressure in the piston drops below a predetermined value.

These and other objects and advantages of the invention will become apparent from the following description and accompanying drawings.

In the drawings:

FIG. 1 is a longitudinal, cross sectional view of a fluid actuated crimping tool having a full stroke compelling mechanism in accordance with the present invention, showing the piston in a retracted position;

FIG. 2 is a fragmentary, longitudinal, cross sectional 70 view of the tool embodying the present invention, showing the piston in a partially advanced position;

3,410,180 Patented Nov. 12, 1968 ice FIG. 3 is a longitudinal, cross sectional view of the fluid actuated crimping tool embodying the present invention, showing the piston in a fully advanced position;

FIG. 4 is a cross sectional view, the plane of the section being indicated by the line 44 in FIG. 2; and

FIG. 5 is an exploded perspective View of the jaw elements.

Referring now to the drawings, a fluid actuated crimping tool is illustrated. The tool 10 includes a body portion 11 having a cylindrical bore 12 therein. The bore 12 is closed at one end by a backing plate 13 and at the other end by a front baflie or web 14. The backing plate 13 is restrained against longitudinal movement in either direction by C-rings 15 and 16, and the front web is restrained against outward movement in one direction by a C-ring 17. Movement of the front web 14 inwardly is prevented by frictional resistance and/or air pressure, as will hereinafter become apparent.

The front web 14 is provided with an axial bore 18 and a piston rod 19 is mounted for reciprocation within the bore 18. The piston rod 19 is provided with a piston head 20 and the piston head 20 is provided with a recessed face portion 21. The piston rod 19 is provided with a bore 22 which is threaded at one end and which receives a stud 23. The stud 23- connects the piston rod 19 to a wedge cam 24.

A conventional, manually operated valve 25 is attached to the backing plate 13. The valve 25 includes a body 26 and a valve spool 27 slidably mounted in a bore 28 in the body 26. A pressure inlet port 29 is drilled into the body 26 and communicates with the bore 28. The port 29 is threaded 'for connection to a suitable fluid pressure source. The body 26 is further provided with a port 30 for supplying fluid under pressure to the piston head 20. The port 30 communicates with a bore 31 in the end plate 13, and the bore 31 in turn communicates with the piston head 20.

In the position illustrated in FIG. 1, the passage 31 is blocked from the source of pressurized air by the valve spool 27, which is positioned to connect the passage 31 through the port 30 to an exhaust passage 32 which is open to the atmosphere. In this position, however, the valve spool 27 is biased downwardly by a spring 33, as viewed in FIG. 1, so that the passage 29 and, therefore, the source of fluid pressure is in communication with a passage 34 which leads to a chamber 35 which is defined by the front web 14 and the piston head 20. The spool 27 may be shifted upwardly, as viewed in FIG. 1, by pressing a handle 36 inwardly toward the body 11. The handle 36 is normally blocked against this inward movement by a safety latch 37. The safety latch 37 may be released by pulling this latch outwardly against the bias of a spring 38 to release the latch 37 from engagement with a pin 39 so that the latch 37 may be swung away from the body 11.

When the handle 36 is pressed toward the body 11, the valve spool 27 is moved upwardly against the bias of the spring 33. As may be seen in FIG. 3, the valve spool has been moved upwardly and the inlet port 29 is connected to the port 30. The passageway 34, furthermore, is then ported to the atmosphere through a port 40.

When the port 30 is connected to the source of fluid pressure, the pressure is applied to the piston head 20 to drive the piston ,rod 19 and the wedge cam 24 forwardly.

0 As the piston head 20 is driven forwardly in this manner,

air is exhausted ahead of the piston head 20 through a passageway 41 and the passageway 34.

The wedge cam 24 is positively retracted by releasing the handle 36. When the handle is released, the spring 33 returns the spool 27 to the position shown in FIG. 1, and the port 29 is connected to the passageway 34 to pressurize the chamber 35 and thereby drive the piston 19 back to the position indicated in FIG. 1. The pressure which had been employed to drive the piston forwardly is exhausted through the port 30 and the exhaust passage 32. Thus, it may be seen that by pressing the handle 36 toward the body 11, the wedge cam 24 is driven forwardly with a force that is a function of the area of the piston head 20; and when the handle 36 is released, the wedge cam 24 is driven rearwardldy by the application of pressure to the piston head 20.

When the wedge cam 24 is driven forwardly in the manner previously indicated, a pair of jaws 42 and 43 is closed and these jaws are opened upon retraction of the wedge cam 24. The jaws 42 and 43 may be designed to perform any of a variety of forming or fabricating operations. In the drawings, however, the jaws 42 and 43 are of the type which are intended to crimp the ferrule portion of an electrical connector to an electrical conductor and its surrounding insulation.

The jaw 42 includes a jaw plate 44, and the jaw 43 includes a jaw plate 45, which coopenates with the plate 44. The jaw plate 44 and 45 are each disposed between and pivotally connected to a pair of end blocks 46 and 47 by pivot pins 48 and 49 which extend through both end blocks and respectively through the jaw plates 44 and 45. The crimping jaws 42 and 43 further include a pair of insulation crimping plates 50 and 51 and the pins 48 and 49 also extend through these crimping plates. The insulation crimping plates 50 and 51 are respectively fixed to the jaw plates 44 and 45 by cap screws 52 and 53. The jaw plates 44 and 45 and the insulation crimping plates 50 and 51 are pivoted for relative rocking movement about a rocking pin 54 interposed between and engaged by concave edge portions of all four of these jaw plates and insulation crimping plates. The pin 54 serves to hold the jaws 42 and 43 in alignment during jaw closure to insure that the jaws will cooperate to define the desired ferrule crimping surface.

The jaw plates 44 and 45 are provided with opposed, ferrule forming die portions 55 and 56, respectively, which may be designed to provide a crimp of any desired configuration to the ferrule portion of an electrical connector when the jaws are closed. The crimping plates 50 and 51 are also provided with opposed ferrule forming die portions 57 and 58, respectively. The die portions 57 and 58 are intended to crimp the insulation sleeve of an electrical connector onto the insulation covering of the electrical conductor.

The jaws 42 and 43 and the end blocks 46 and 47 are fixed to the end of the body 11 by a pair of screws 59 which extend from opposite sides through the body 11 and into the end blocks 46 and 47, respectively. The blocks 46 and 47 are respectively mounted in recesses 60 and 61, which are provided in opposed inner faces of a yoke formed on the end of the body 11. The jaws 42 and 43 are mounted so that the jaw plates 44 and 45 are in planar alignment with the axis of the piston 19 and so that a pair of cam faces 62 and 63 on the wedge cam 24 pass on either side of the jaw plates 44 and 45 when the wedge cam 24 is driven forwardly in the previously described manner.

A pair of cam followers 64 and 65 are rotatably mounted on a pin 66 which extends through the lower end of the jaw plate 44. A pin 67 (FIGS. 1, 2, and 3) extends through the lower end of the jaw plate 45. A cam follower 68 (FIGS. 1, 2, and 3) is provided on one end of the pin 67 and another cam fol-lower (not shown but corresponding to the cam follower 65) is provided on the other end of the pin 67.

The upper ends of the jaws 42 and 43 are normally biased apart by a spring 69, which is connected to the ends of the pins 66 and 67 to urge the lower portions of the jaws 42 and 43 together.

When the wedge cam 24 is driven forwardly in the previously described manner, the cam followers 64 and 65' are separated from the cam follower 68 and its corresponding cam follower (not shown) by the cam surfaces 4 62 and 63 so that the jaws 42 and 43 will be rocked about the rocking pin 54 as a fulcrum and closed to define a desired ferrule crimp. Conversely, when the wedge cam 24 is retracted in the previously described manner, the spring 69 urges the jaws 42 and 43 apart.

There is provided means to insure that the piston head, and therefore the piston rod 19 and its wedge cam 24, will travel forwardly a predetermined extent. Frequently, an operator of the tool may not depress the handle 36 for a sufficient time period to permit the piston 20 to complete its full forward travel. In such an instance, the piston may be retracted prior to the completion of the crimping operation. In order to prevent any such occurrence, the tool 10 is provided with a full stroke compelling mechanism 70. The full stroke compelling mechanism 70 comprises a valve 71 having a valve stem 72 and a relatively large head 73. The valve stem 72 is slidably mounted in a bore 74 which extends through the front web 14. There are provided a plurality of radial slots 75 which extend along the length of the bore 74 to provide fluid communication between a first counterbore 76 and a second counterbore 77. It should be appreciated that other means may be provided to provide fluid communication between the counterbores 76 and 77. For example, the valve stem may have a fiat portion along its cylindrical sidewall which de fines a passage with a smooth-walled cylindrical bore. The first counterbore is provided with an O-ring seal 78. The valve 71 is movable between a first position (FIG. 3) wherein the head 73 is seated within the first counterbore 76 and a second position (FIG. 2) wherein the head 73 is displaced outwardly from the first counterbore 76 and wherein a snap ring 79 on one end of the rod 72 is received by the second counterbore 77. The valve 71 is normally biased toward its first position by a cantilever leaf spring 80 which is arcuate and which is fixed at one end to the C-ring 17. Other biasing means, such as a coil spring, may be employed to urge the valve 71 toward its first position.

When the tool 10 is in an at-rest position, as shown in FIG. 1, the chamber 35 is pressurized and the valve 71 is seated since the head 73 has a cross sectional area which results in a force at a predetermined pressure which is sufficient to overcome the bias of the spring 80. When the handle 36 is depressed to exhaust air from the chamber 35 and to simultaneously apply pressure behind the piston head 20, the valve 71 is opened by the spring 80 so that fluid pressure is exhausted through the passageway 41 and through the slots 75. The valve 71 remains open until the piston head 20 strikes the head 73 at the end of its stroke to close the valve 71 against the bias of the spring 80. After the piston head 20 attains the position illustrated in FIG. 3, it may be driven backwardly by releasing the handle 36 to thereby admit fluid pressure to the chamber 35. If, on the other hand, the piston head 20 does not reach the end of its stroke by, for example, the premature release of the handle 36, the valve 71 will not be closed by the piston head 20. In this instance, the retracting air pressure in the chamber 35 will be not drive the piston head rearwardly but will, rather, be exhausted through the slots 75 to the atmosphere, since the fluid pressure on the valve 71 has a force corresponding to the product of the pressure in the chamber 35 and the cross sectional area of the rod 72. The spring 80, therefore, it designed to exert a force on the rod 72 which is greater than the force resulting from the product of the pressure in the chamber 35 and the cross sectional area of the rod 72, but which force is less than the force resulting from the product of the pressure in the chamber 35 and the cross sectional area of the head 73. If, therefore, the piston rod 19 fails to retpact when the handle 36 is released, the operator must again depress the handle 36 to permit the piston head 20 to attain its full stroke.

The valve 71 also serves to detect any drop in line pressure past a predetermined value. Such a drop in line pressure would not be easily detected by the operator of the hand tool 10, but would result in defectively crimped terminals and connectors. If the line pressure drops to a value which will permit the spring 80 to open the valve 71 against the force exerted on the head 73, the tool may not be operated until the line pressure is restored.

It should be appreciated that the full stroke impelling mechanism according to this invention may be employed on devices other than fluid actuated crimping tools where it is desirable or necessary for a piston to travel a predetermined distance within its cylinder prior to retraction of the piston.

The invention, therefore, is not restricted to the slavish imitation of each and every one of the details described above, which have been set 'forth merely by way of example. Obviously, devices may be provided which change, eliminate, or add certain specific details without departing from the invention.

What is claimed is:

1. In combination with a fluid operated piston slidably mounted for reciprocation between first and second positions within a cylinder upon the alternate application and exhaustion of fluid pressure to and from a chamber defined by a face of said piston, a portion of said cylinder, and by a wall closing one end of said cylinder, said piston being moved away from said wall upon the application of fluid pressure to said chamber and being moved toward said wall upon the exhaustion of fluid pressure from said chamber, a full stroke complelling mechanism for insuring the movement of said piston toward said wall and to a predetermined position with respect to said wall prior to movement of said piston away from said wall, said full stroke complelling mechanism comprising a passage through said wall from said chamber to the atmosphere, pressure-responsive valve means in said passage, said valve means being operable between an open position venting said one chamber to the atmosphere and a closed position, means biasing said valve means toward its open position, means on the piston to close said valve means (said valve being closed) in response to the movement of said piston to said predetermined position with respect to said wall, said valve means being held in a closed position by the application of fluid pressure to said chamber to move said piston away from said wall but remaining open under said fluid pressure if said pressure is applied prior to closure of the valve by the piston.

2. A full stroke compelling mechanism according to claim 1 wherein said valve means comprises a valve comprising a head portion having a relatively large cross sectional areaexposed to said chamber and a stem portion having a relatively small cross sectional area exposed to the atmosphere.

3. A full stroke compelling mechanism according to claim 2 wherein said stem portion extends through said wall and together with said wall defines said passage.

4. A full stroke compelling mechanism according to claim 3 wherein said head portion is received by a counterbore in said wall when said valve is in its closed position and wheren said counterbore includes sealing means to isolate said passage from said chamber when said head is seated in said counterbore.

5. A full stroke compelling mechanism according to claim 1 wherein said biasing means is a leaf spring.

6. A full stroke compelling mechanism according to claim 4 wherein said biasing means is a leaf spring which engages said stern.

References Cited UNITED STATES PATENTS 2,591,492 4/ 1952 Anderson 9 l407 2,671,434 3/ 1954 Schmiedeskamp 91273 2,699,153 1/1955 Russell 91273 2,755,876 7/1956 Muller 91-442 2,797,550 7/1957 Stelzer 91442 3,299,968 1/1967 Cunningham 91-341 EDGAR W. GEOGHEGAN, Primary Examiner. B. L. ADAMS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,410,180 November 12, 1968 Paul J. Spangler, et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 8, "rearwardldy" should read rearwardly Column 4, line 58, cancel "be". Column 5, line 28, "complelling should read compelling line 32, "complelling" should read compelling lines 38 and 39 cancel (said valve being closed) Signed and sealed this 10th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR. 

